An apparatus for rolling strip having a periodically fluctuating strip thickness has a roll stand with a set of rollers and an adjustment actuator for adjusting the gap of the set of rollers, to which roller gap the strip is fed from an unwinder with an initial thickness on the intake side and from which roller gap the strip is fed with the respective desired final thickness to a winder on the output side with the final thickness being determined by the roller gap.
An apparatus of this type as well as a method of this generic type are known from the prior art. In such an apparatus and method, strip materials made of strip steel are usually processed. One apparatus of this generic type is known particularly from EP 1 121 990. This prior art describes a cost-effective possibility for unwinding under tension strip that has been wound into coils, reducing the strip thickness, and subsequently winding the strip up again under tension, with a relatively constant strip thickness being provided on the intake side and a periodically fluctuating strip thickness being desired on the output side. In that printed publication, this is achieved by providing a compensating or dancer roll between the unwinder and the roll stand as well as between the roll stand and the winder, around which the strip is fed in a loop and which are force-controlled at a constant circumferential speed by the rollers of the roll stand, which determine the roller gap, in order to set the desired strip tension. It is also necessary for the winder and unwinder to be speed-controlled.
While this proposed apparatus is usable in principle, the force control of the compensating or dancer rolls in particular is only possible with a relatively large investment of time, with the consequence that rolling defects resulting from the periodically fluctuating strip thickness cannot be compensated for quickly enough. This means that strips of periodically fluctuating thickness produced with the apparatus are faulty due to the high travel speed.
The speed control of the winder and unwinder is also laborious and can also lead to faults during the operation of the corresponding apparatus.